Many instances of the same program

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  • =?Utf-8?B?QnJvbmlzbGF2?=
    #1

    Many instances of the same program

    I need to run more then 1 instance of the same program but also I need to
    know which instance is running.
    In C++ code was:
    int nInstance = 0;
    char szAppName[32];


    m_dwMutexReturn = ERROR_ALREADY_E XISTS;
    while (( m_dwMutexReturn == ERROR_ALREADY_E XISTS ) && ( nInstance <
    MAXINSTANCES ))
    {
    nInstance++;
    itoa( nInstance, szTemp, 10 );
    strcpy( szAppName, "ProductEng ine" );
    strcat( szAppName, szTemp );
    m_hMutex = CreateMutex( NULL, TRUE, szAppName );
    m_dwMutexReturn = GetLastError();
    }

    if ( nInstance == MAXINSTANCES )
    m_sState->nInstance = 1;
    else
    m_sState->nInstance = nInstance;
    but I can't port this code to C#.
    Somebody knows how to do it?

    Tags: None
    • Nicholas Paldino [.NET/C# MVP]
      #2
      Re: Many instances of the same program

      Bronislav,

      There are a number of examples of how to do this on the web. Have you
      taken a look at the Mutex class? It will give you everything you need to do
      to replicate this behavior.


      --
      - Nicholas Paldino [.NET/C# MVP]
      - mvp@spam.guard. caspershouse.co m

      "Bronislav" <Bronislav@disc ussions.microso ft.comwrote in message
      news:2D3B8599-9DA9-4D0C-A526-2FAE00EBB7A2@mi crosoft.com...
      >I need to run more then 1 instance of the same program but also I need to
      know which instance is running.
      In C++ code was:
      int nInstance = 0;
      char szAppName[32];
      >
      >
      m_dwMutexReturn = ERROR_ALREADY_E XISTS;
      while (( m_dwMutexReturn == ERROR_ALREADY_E XISTS ) && ( nInstance <
      MAXINSTANCES ))
      {
      nInstance++;
      itoa( nInstance, szTemp, 10 );
      strcpy( szAppName, "ProductEng ine" );
      strcat( szAppName, szTemp );
      m_hMutex = CreateMutex( NULL, TRUE, szAppName );
      m_dwMutexReturn = GetLastError();
      }
      >
      if ( nInstance == MAXINSTANCES )
      m_sState->nInstance = 1;
      else
      m_sState->nInstance = nInstance;
      but I can't port this code to C#.
      Somebody knows how to do it?
      >

        Comment

        • =?Utf-8?B?QnJvbmlzbGF2?=
          #3
          Re: Many instances of the same program

          The Mutex class in my understanding is not complete analog of the CreateMutex
          API
          because it not allowed to create difference instances of the programm with
          the different name and I need exactly this.

          "Nicholas Paldino [.NET/C# MVP]" wrote:
          Bronislav,
          >
          There are a number of examples of how to do this on the web. Have you
          taken a look at the Mutex class? It will give you everything you need to do
          to replicate this behavior.
          >
          >
          --
          - Nicholas Paldino [.NET/C# MVP]
          - mvp@spam.guard. caspershouse.co m
          >
          "Bronislav" <Bronislav@disc ussions.microso ft.comwrote in message
          news:2D3B8599-9DA9-4D0C-A526-2FAE00EBB7A2@mi crosoft.com...
          I need to run more then 1 instance of the same program but also I need to
          know which instance is running.
          In C++ code was:
          int nInstance = 0;
          char szAppName[32];


          m_dwMutexReturn = ERROR_ALREADY_E XISTS;
          while (( m_dwMutexReturn == ERROR_ALREADY_E XISTS ) && ( nInstance <
          MAXINSTANCES ))
          {
          nInstance++;
          itoa( nInstance, szTemp, 10 );
          strcpy( szAppName, "ProductEng ine" );
          strcat( szAppName, szTemp );
          m_hMutex = CreateMutex( NULL, TRUE, szAppName );
          m_dwMutexReturn = GetLastError();
          }

          if ( nInstance == MAXINSTANCES )
          m_sState->nInstance = 1;
          else
          m_sState->nInstance = nInstance;
          but I can't port this code to C#.
          Somebody knows how to do it?
          >
          >
          >

            Comment

            • Nicholas Paldino [.NET/C# MVP]
              #4
              Re: Many instances of the same program

              Bronislav,

              You can call the static OpenExisting method on the Mutex class to get a
              named mutex instance. If it doesn't exist, then you can catch the
              WaitHandleCanno tBeOpenedExcept ion instance that is thrown and then create a
              new one.

              Now, you do run the risk of running into a race condition here, as two
              instances of the app can try to open a mutex that doesn't exist, which is
              different from the call to CreateMutex. If you want to avoid this race
              condition, declare the CreateMutex API function and call it through the
              P/Invoke layer, getting the handle. Then, create a new Mutex instance, and
              assign the handle to that if you want to use it.


              --
              - Nicholas Paldino [.NET/C# MVP]
              - mvp@spam.guard. caspershouse.co m

              "Bronislav" <Bronislav@disc ussions.microso ft.comwrote in message
              news:7FF9826E-4D80-40B6-8B9F-8E5164F9706E@mi crosoft.com...
              The Mutex class in my understanding is not complete analog of the
              CreateMutex
              API
              because it not allowed to create difference instances of the programm with
              the different name and I need exactly this.
              >
              "Nicholas Paldino [.NET/C# MVP]" wrote:
              >
              >Bronislav,
              >>
              > There are a number of examples of how to do this on the web. Have
              >you
              >taken a look at the Mutex class? It will give you everything you need to
              >do
              >to replicate this behavior.
              >>
              >>
              >--
              > - Nicholas Paldino [.NET/C# MVP]
              > - mvp@spam.guard. caspershouse.co m
              >>
              >"Bronislav" <Bronislav@disc ussions.microso ft.comwrote in message
              >news:2D3B859 9-9DA9-4D0C-A526-2FAE00EBB7A2@mi crosoft.com...
              >I need to run more then 1 instance of the same program but also I need
              >to
              know which instance is running.
              In C++ code was:
              int nInstance = 0;
              char szAppName[32];
              >
              >
              m_dwMutexReturn = ERROR_ALREADY_E XISTS;
              while (( m_dwMutexReturn == ERROR_ALREADY_E XISTS ) && ( nInstance <
              MAXINSTANCES ))
              {
              nInstance++;
              itoa( nInstance, szTemp, 10 );
              strcpy( szAppName, "ProductEng ine" );
              strcat( szAppName, szTemp );
              m_hMutex = CreateMutex( NULL, TRUE, szAppName );
              m_dwMutexReturn = GetLastError();
              }
              >
              if ( nInstance == MAXINSTANCES )
              m_sState->nInstance = 1;
              else
              m_sState->nInstance = nInstance;
              but I can't port this code to C#.
              Somebody knows how to do it?
              >
              >>
              >>
              >>

                Comment

                • =?Utf-8?B?QnJvbmlzbGF2?=
                  #5
                  Re: Many instances of the same program

                  I tried to do exactly that but I cannot find how to call CreateMutex through
                  p-invoke
                  I tried both declaretions

                  /*
                  [DllImport("kern el32.dll", SetLastError=tr ue)]
                  private static extern int CreateMutexA(
                  ref SECURITY_ATTRIB UTES lpMutexAttribut es,
                  int bInitialOwner,
                  string lpName);
                  */
                  [DllImport("kern el32.dll", SetLastError=tr ue)]
                  private static extern System.IntPtr CreateMutexA(
                  out int lpMutexAttribut es,
                  bool bInitialOwner,
                  string lpName);
                  but when I call CreateMutex
                  lhndlRetHandle = CreateMutexA(nu ll, true, lstrAppName);
                  It give me error that first parameter cannot be NULL
                  Thanks.


                  "Nicholas Paldino [.NET/C# MVP]" wrote:
                  Bronislav,
                  >
                  You can call the static OpenExisting method on the Mutex class to get a
                  named mutex instance. If it doesn't exist, then you can catch the
                  WaitHandleCanno tBeOpenedExcept ion instance that is thrown and then create a
                  new one.
                  >
                  Now, you do run the risk of running into a race condition here, as two
                  instances of the app can try to open a mutex that doesn't exist, which is
                  different from the call to CreateMutex. If you want to avoid this race
                  condition, declare the CreateMutex API function and call it through the
                  P/Invoke layer, getting the handle. Then, create a new Mutex instance, and
                  assign the handle to that if you want to use it.
                  >
                  >
                  --
                  - Nicholas Paldino [.NET/C# MVP]
                  - mvp@spam.guard. caspershouse.co m
                  >
                  "Bronislav" <Bronislav@disc ussions.microso ft.comwrote in message
                  news:7FF9826E-4D80-40B6-8B9F-8E5164F9706E@mi crosoft.com...
                  The Mutex class in my understanding is not complete analog of the
                  CreateMutex
                  API
                  because it not allowed to create difference instances of the programm with
                  the different name and I need exactly this.

                  "Nicholas Paldino [.NET/C# MVP]" wrote:
                  Bronislav,
                  >
                  There are a number of examples of how to do this on the web. Have
                  you
                  taken a look at the Mutex class? It will give you everything you need to
                  do
                  to replicate this behavior.
                  >
                  >
                  --
                  - Nicholas Paldino [.NET/C# MVP]
                  - mvp@spam.guard. caspershouse.co m
                  >
                  "Bronislav" <Bronislav@disc ussions.microso ft.comwrote in message
                  news:2D3B8599-9DA9-4D0C-A526-2FAE00EBB7A2@mi crosoft.com...
                  I need to run more then 1 instance of the same program but also I need
                  to
                  know which instance is running.
                  In C++ code was:
                  int nInstance = 0;
                  char szAppName[32];


                  m_dwMutexReturn = ERROR_ALREADY_E XISTS;
                  while (( m_dwMutexReturn == ERROR_ALREADY_E XISTS ) && ( nInstance <
                  MAXINSTANCES ))
                  {
                  nInstance++;
                  itoa( nInstance, szTemp, 10 );
                  strcpy( szAppName, "ProductEng ine" );
                  strcat( szAppName, szTemp );
                  m_hMutex = CreateMutex( NULL, TRUE, szAppName );
                  m_dwMutexReturn = GetLastError();
                  }

                  if ( nInstance == MAXINSTANCES )
                  m_sState->nInstance = 1;
                  else
                  m_sState->nInstance = nInstance;
                  but I can't port this code to C#.
                  Somebody knows how to do it?

                  >
                  >
                  >
                  >
                  >
                  >

                    Comment

                    • Nicholas Paldino [.NET/C# MVP]
                      #6
                      Re: Many instances of the same program

                      Well, you can declare lpMutexAttribut es as IntPtr if you are going to
                      pass null. Also, you should declare the bInitialOwner parameter as bool,
                      and you should indicate the version of the function you want to use in the
                      DllImport attribute and you should set the return type to IntPtr (since it
                      is a handle). Putting it all together, you should have:

                      [DllImport("kern el32.dll", SetLastError=Tr ue, CharSet=CharSet .Auto)]
                      private static extern IntPtr CreateMutex(Int Ptr lpMutexAttribut es, bool
                      bInitialOwner, string lpName);

                      Then, you can pass IntPtr.Zero to the first parameter.


                      --
                      - Nicholas Paldino [.NET/C# MVP]
                      - mvp@spam.guard. caspershouse.co m

                      "Bronislav" <Bronislav@disc ussions.microso ft.comwrote in message
                      news:0CD9F855-C2F6-4D24-9208-917BF33DEEC4@mi crosoft.com...
                      >I tried to do exactly that but I cannot find how to call CreateMutex
                      >through
                      p-invoke
                      I tried both declaretions
                      >
                      /*
                      [DllImport("kern el32.dll", SetLastError=tr ue)]
                      private static extern int CreateMutexA(
                      ref SECURITY_ATTRIB UTES lpMutexAttribut es,
                      int bInitialOwner,
                      string lpName);
                      */
                      [DllImport("kern el32.dll", SetLastError=tr ue)]
                      private static extern System.IntPtr CreateMutexA(
                      out int lpMutexAttribut es,
                      bool bInitialOwner,
                      string lpName);
                      but when I call CreateMutex
                      lhndlRetHandle = CreateMutexA(nu ll, true, lstrAppName);
                      It give me error that first parameter cannot be NULL
                      Thanks.
                      >
                      >
                      "Nicholas Paldino [.NET/C# MVP]" wrote:
                      >
                      >Bronislav,
                      >>
                      > You can call the static OpenExisting method on the Mutex class to get
                      >a
                      >named mutex instance. If it doesn't exist, then you can catch the
                      >WaitHandleCann otBeOpenedExcep tion instance that is thrown and then create
                      >a
                      >new one.
                      >>
                      > Now, you do run the risk of running into a race condition here, as
                      >two
                      >instances of the app can try to open a mutex that doesn't exist, which is
                      >different from the call to CreateMutex. If you want to avoid this race
                      >condition, declare the CreateMutex API function and call it through the
                      >P/Invoke layer, getting the handle. Then, create a new Mutex instance,
                      >and
                      >assign the handle to that if you want to use it.
                      >>
                      >>
                      >--
                      > - Nicholas Paldino [.NET/C# MVP]
                      > - mvp@spam.guard. caspershouse.co m
                      >>
                      >"Bronislav" <Bronislav@disc ussions.microso ft.comwrote in message
                      >news:7FF9826 E-4D80-40B6-8B9F-8E5164F9706E@mi crosoft.com...
                      The Mutex class in my understanding is not complete analog of the
                      CreateMutex
                      API
                      because it not allowed to create difference instances of the programm
                      with
                      the different name and I need exactly this.
                      >
                      "Nicholas Paldino [.NET/C# MVP]" wrote:
                      >
                      >Bronislav,
                      >>
                      > There are a number of examples of how to do this on the web. Have
                      >you
                      >taken a look at the Mutex class? It will give you everything you need
                      >to
                      >do
                      >to replicate this behavior.
                      >>
                      >>
                      >--
                      > - Nicholas Paldino [.NET/C# MVP]
                      > - mvp@spam.guard. caspershouse.co m
                      >>
                      >"Bronislav" <Bronislav@disc ussions.microso ft.comwrote in message
                      >news:2D3B859 9-9DA9-4D0C-A526-2FAE00EBB7A2@mi crosoft.com...
                      >I need to run more then 1 instance of the same program but also I
                      >need
                      >to
                      know which instance is running.
                      In C++ code was:
                      int nInstance = 0;
                      char szAppName[32];
                      >
                      >
                      m_dwMutexReturn = ERROR_ALREADY_E XISTS;
                      while (( m_dwMutexReturn == ERROR_ALREADY_E XISTS ) && ( nInstance <
                      MAXINSTANCES ))
                      {
                      nInstance++;
                      itoa( nInstance, szTemp, 10 );
                      strcpy( szAppName, "ProductEng ine" );
                      strcat( szAppName, szTemp );
                      m_hMutex = CreateMutex( NULL, TRUE, szAppName );
                      m_dwMutexReturn = GetLastError();
                      }
                      >
                      if ( nInstance == MAXINSTANCES )
                      m_sState->nInstance = 1;
                      else
                      m_sState->nInstance = nInstance;
                      but I can't port this code to C#.
                      Somebody knows how to do it?
                      >
                      >>
                      >>
                      >>
                      >>
                      >>
                      >>

                        Comment

                        • =?Utf-8?B?QnJvbmlzbGF2?=
                          #7
                          Re: Many instances of the same program

                          Thanks

                          "Nicholas Paldino [.NET/C# MVP]" wrote:
                          Well, you can declare lpMutexAttribut es as IntPtr if you are going to
                          pass null. Also, you should declare the bInitialOwner parameter as bool,
                          and you should indicate the version of the function you want to use in the
                          DllImport attribute and you should set the return type to IntPtr (since it
                          is a handle). Putting it all together, you should have:
                          >
                          [DllImport("kern el32.dll", SetLastError=Tr ue, CharSet=CharSet .Auto)]
                          private static extern IntPtr CreateMutex(Int Ptr lpMutexAttribut es, bool
                          bInitialOwner, string lpName);
                          >
                          Then, you can pass IntPtr.Zero to the first parameter.
                          >
                          >
                          --
                          - Nicholas Paldino [.NET/C# MVP]
                          - mvp@spam.guard. caspershouse.co m
                          >
                          "Bronislav" <Bronislav@disc ussions.microso ft.comwrote in message
                          news:0CD9F855-C2F6-4D24-9208-917BF33DEEC4@mi crosoft.com...
                          I tried to do exactly that but I cannot find how to call CreateMutex
                          through
                          p-invoke
                          I tried both declaretions

                          /*
                          [DllImport("kern el32.dll", SetLastError=tr ue)]
                          private static extern int CreateMutexA(
                          ref SECURITY_ATTRIB UTES lpMutexAttribut es,
                          int bInitialOwner,
                          string lpName);
                          */
                          [DllImport("kern el32.dll", SetLastError=tr ue)]
                          private static extern System.IntPtr CreateMutexA(
                          out int lpMutexAttribut es,
                          bool bInitialOwner,
                          string lpName);
                          but when I call CreateMutex
                          lhndlRetHandle = CreateMutexA(nu ll, true, lstrAppName);
                          It give me error that first parameter cannot be NULL
                          Thanks.


                          "Nicholas Paldino [.NET/C# MVP]" wrote:
                          Bronislav,
                          >
                          You can call the static OpenExisting method on the Mutex class to get
                          a
                          named mutex instance. If it doesn't exist, then you can catch the
                          WaitHandleCanno tBeOpenedExcept ion instance that is thrown and then create
                          a
                          new one.
                          >
                          Now, you do run the risk of running into a race condition here, as
                          two
                          instances of the app can try to open a mutex that doesn't exist, which is
                          different from the call to CreateMutex. If you want to avoid this race
                          condition, declare the CreateMutex API function and call it through the
                          P/Invoke layer, getting the handle. Then, create a new Mutex instance,
                          and
                          assign the handle to that if you want to use it.
                          >
                          >
                          --
                          - Nicholas Paldino [.NET/C# MVP]
                          - mvp@spam.guard. caspershouse.co m
                          >
                          "Bronislav" <Bronislav@disc ussions.microso ft.comwrote in message
                          news:7FF9826E-4D80-40B6-8B9F-8E5164F9706E@mi crosoft.com...
                          The Mutex class in my understanding is not complete analog of the
                          CreateMutex
                          API
                          because it not allowed to create difference instances of the programm
                          with
                          the different name and I need exactly this.

                          "Nicholas Paldino [.NET/C# MVP]" wrote:

                          Bronislav,
                          >
                          There are a number of examples of how to do this on the web. Have
                          you
                          taken a look at the Mutex class? It will give you everything you need
                          to
                          do
                          to replicate this behavior.
                          >
                          >
                          --
                          - Nicholas Paldino [.NET/C# MVP]
                          - mvp@spam.guard. caspershouse.co m
                          >
                          "Bronislav" <Bronislav@disc ussions.microso ft.comwrote in message
                          news:2D3B8599-9DA9-4D0C-A526-2FAE00EBB7A2@mi crosoft.com...
                          I need to run more then 1 instance of the same program but also I
                          need
                          to
                          know which instance is running.
                          In C++ code was:
                          int nInstance = 0;
                          char szAppName[32];


                          m_dwMutexReturn = ERROR_ALREADY_E XISTS;
                          while (( m_dwMutexReturn == ERROR_ALREADY_E XISTS ) && ( nInstance <
                          MAXINSTANCES ))
                          {
                          nInstance++;
                          itoa( nInstance, szTemp, 10 );
                          strcpy( szAppName, "ProductEng ine" );
                          strcat( szAppName, szTemp );
                          m_hMutex = CreateMutex( NULL, TRUE, szAppName );
                          m_dwMutexReturn = GetLastError();
                          }

                          if ( nInstance == MAXINSTANCES )
                          m_sState->nInstance = 1;
                          else
                          m_sState->nInstance = nInstance;
                          but I can't port this code to C#.
                          Somebody knows how to do it?

                          >
                          >
                          >
                          >
                          >
                          >
                          >
                          >
                          >

                            Comment

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